Not applicable.
Alternative medicine approaches to the treatment of a variety of physical and mental conditions have been the subject of substantial investigation and interest. See: Journal of the American Medical Association (1998), 280 (18). Nontraditional techniques in the management of pain have ranged from classic acupuncture to the electrical stimulation of tissue. In the latter regard, the efficacy of electrical stimulation from skin surface attached electrodes have been the subject of a substantial amount of investigation. Referred to generally as transcutaneous electrical nerve stimulation (TENS), typically a relatively low level of current, for example, in the milliamp range which is manifested as a squarewave is introduced to some select region of the peripheral nervous system for a prescribed treatment interval. The frequency of this squarewave signal is relatively low, ranging generally from a few Hertz to about 100 Hertz and patient response to the application of such low frequency currents at the skin has been described as an unpleasant experience.
Somewhat recently, a combination of electrical stimulation and acupuncture has evolved. This technique differs from traditional acupuncture in that the needle itself is not the focus of treatment, instead, it serves as a conductor of electricity. One approach with electroacupuncture has been described as percutaneous electrical nerve stimulation (PENS). This PENS therapy utilizes acupuncture-like needle probes positioned in the soft tissue to stimulate peripheral sensory nerves at the dermatomal levels.
In the 1970s, Limoge, working in France, evolved an electroanesthesia electroanalgesia approach involving a different form of stimulation sometimes referred to as xe2x80x9cLimoge currentsxe2x80x9d wherein, for example, a pulse cycle comprising pulses consisting of a positive wave for 2 xcexcS is followed by a negative wave of 4 xcexcS. The group has a period duration of 6 xcexcS corresponding to 166 kHz. These groups have been referred to as bi-phasic balanced currents. They are gated on for four milliseconds followed by an off period of six milliseconds. The total cycle period thus is ten milliseconds corresponding to a 100 Hz gating cycle or burst frequency.
The integrals of the positive high frequency pulses and the negative high frequency pulses are maintained in balance. This results in a zero net applied current and eliminates or substantially abates a potential for electrophoresis. The current intensity generally will be from about 220 mA to about 250 mA peak to peak. In general, application of the current is by transcranial electrical stimulation (TCES) which is applied to the head through a frontal electrode and two posterior electrodes at the level of the mastoid bones. TCES treatment evidences no apparent side effects and has been used with very positive results in abdominal, urological gynecolgical and orthopedic surgery and traumatology and in addiction withdrawal therapy. TCES has been shown to enhance the potency of conventional pharmaceuticals during surgery and to evoke a reduction in the need for opiate analgesic during neuroleptanalgesia. Mathematical analysis of the Limoge currents indicates that the use of high frequency currents allow deep penetration of the electric field into the brain. It has been thought that the dielectric properties of biological tissue enables, in situ, the high frequency current combination with low frequency currents is responsible for the analgesic potentiaton. See the following publications:
Limoge, A., An introduction to electroanaesthsia. In: R. M. Johnson (Ed.), University Park Press, Baltimore, Md., 1975, pp. 1-121.
Limoge, A., Louville, Y., Barritault, L., Cazalaa, J. B. and Atinault, A., Electrical anesthesia. In: J. Spierdijk, S. A. Feldman, H. Mattie and T. H. Stanley (Eds.), Developments in Drug Used in Anesthesia, Leiden University Press, Leiden, 1981, pp. 121-134.
Limoge, A. and Boisgontier, M. T., Characteristic of electric currents used in human anesthesiology. In: B. Rybak (Ed.), Advanced Technology, Sijthoff and Noordhoff, German-town, 1979, pp. 437-446.
Champagne, Papiemak, Thierry, and Noviant, Transcutaneous Cranial Electrical Stimulation by Limoge Currents During Labor, Ann. Fr. Anesth. Reanim., Masson Paris, 1984.
Stanley, T. H., Cazalaa, J. A., Atinault, A., Coeytaux, R., Limoge, A. and Louville, Y., Transcutaneous cranial electrical stimulation decreases narcotic requirements during neuroleptic anesthesia and operation in man, Anest. Analg., 61 (1982) 863-866.
Stanley, T. H., Cazalaa, J. A., Limoge, A. and Louville, Y., Transcutaneous cranial electrical stimulation increases the potency of nitrous oxide in humans, Anesthesiology, 57 (1982) 293-297.
Ellison, F., Ellison, W., Daulouede, J. P., Daubech, F. E., Pautrizel, B., Bourgeois, M. and Tignol, J., Opiate withdrawal and electrostimulation double blind experiments, Encephale, 13 (1987) 225-229.
In support of an expanded utilization of the Limoge currents in the control and management of pain and a variety of medical conditions, investigators and practitioners now find need for improved generation equipment with heightened capacities for investigation of variations of the Limoge current signatures or characteristics and for utilization of these variations and their effect for diagnostic applications to treatment as well as therapeutic purposes.
The present invention is addressed to the subject of electrobiological stimulation. It particularly is directed to the introduction of systems, devices and methods which not only support current therapeutic techniques of electrostimulation considered effective, but also provide investigators, including research clinicians, with a support system permitting enhanced research endeavors.
The system has been evolved with a recognition that an electrical waveform can be applied to a load, here tissue, exhibiting variable and unknown electrical impedance characteristics in a manner wherein those electrical characteristics can be analyzed. Those electrical characteristics will correspond with the tissue characteristics of the material constituting such load. For the present investigatory system, that load is the animal head. Expanding upon the electrode stimulation developed by Limoge (TCES) the present system exhibits enhanced procedures and efficiencies for carrying out now established therapeutic protocols. As an adjunct to these features, the system and technique provide apparatus and method with capabilities for supporting both patient stimulation as well as diagnosis and clinical research in electrobiological stimulation technologies. In the latter regard, the instant approach recognizes that rectangular wave comprising high frequency harmonics of base frequency signals with positive-going and negative-going features are combined to exhibit no d.c. term. In general, the ultimately derived waveforms are assembled by gating at a burst frequency. However, when said high frequency is applied to a biological load such as a human head, a resultant current waveform, when compared to the corresponding applied or feed point voltage waveform, will exhibit aberrations representing, for example, impedance characteristics of the cranial region through which current passes. Digitization and analysis of these two waveforms evolves valuable diagnostic data. Such analysis will include Fourier transform definition of both waveforms in conjunction with mathematical analyses thereof which manipulate data representing their differences. Laplace-mathematical operators also provide substantial analysis of the impedance characteristics throughout the region coursed by one or more channels of current flow. As is apparent, as such analysis is applied to an expanding patient population, an important database can be evolved with a library of accessible mathematical parameters, biological parameters and symptom parameters to evoke expanding diagnostic possibilities and accuracies. Thus, the apparatus, system and method of the invention is directed to providing practitioners and researchers an improved therapeutic capability coupled with a unique diagnostic opportunity.
In one embodiment, apparatus is provided for applying current for therapeutic purpose which incorporates a control assembly. That control assembly performs in conjunction with positive and negative voltage converters operating in two channels, as well as a network of voltage and current monitors. The control assembly determines impedance values for each channel and carries out comparison procedures to evaluate not only that impedance, but peak values of voltage and current, overvoltage and overcurrent conditions, and channel balance conditions. Where those operational parameters are beyond specified limits, the apparatus is automatically shutdown. Detection of any d.c. term greater than some limit and resultant shutdown also is made for the safety of the patient.
In another embodiment, a controller is provided which affords the practitioner substantial versatility and waveshape structuring, a feature particularly valuable for carrying out a variety of electrobiologic diagnostic procedures. This controller mathematically processes monitored voltage and current at the feedpoint electrodes to derive a broad variety of electrically defined biological factors. Memory is employed not only to retain such data but also to provide a library of similar data derived from patient populations.
As another feature, the invention provides a method for applying an electrical stimulus transcranially to an animal with skin regions located adjacent a volume of tissular material, comprising the steps of:
(a) providing first and second electrode assemblies of respective first and second polarities;
(b) providing electrical generation apparatus electrically coupled with the first and second electrode assemblies, responsive to a generator input to provide an excitation output, across the first and second electrode assemblies at frequencies and with waveshapes exhibiting given electrical characteristics;
(c) providing a current sensor assembly responsive to the electrical excitation outputs for providing a monitored current value output;
(d) providing a voltage sensor assembly responsive to the electrical excitation outputs for providing a monitored voltage value output;
(e) providing a controller having a memory and a display and controllable to derive a generator input for producing the excitation output exhibiting predetermined frequencies and waveforms;
(f) electrically coupling the first electrode assembly to the first skin surface region;
(g) electrically coupling the second electrode assembly to a second skin surface region spaced from the first skin surface region;
(h) controlling the controller to derive a generator input to produce an excitation output across the tissular volume for a predetermined application interval, such excitation output having electrical characteristics defining the waveform with positive-going and negative-going waveform components combined to exhibit substantially no d.c. term and occurring at a base frequency value and at a burst repetition frequency value less than the base frequency value;
(i) controlling the controller to record in the memory, the monitored voltage output as voltage data corresponding with the electrical characteristic; and
(j) controlling the controller to record in the memory the monitored current output in correspondence with the monitored voltage output as current data corresponding with the electrical characteristics and influenced by the impedance characteristics extant at the volume of tissular material.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.
The invention, accordingly, comprises the apparatus, system and method possessing the construction, combination of elements, arrangement of parts and steps which are exemplified in the following detailed description.